Authorities said New York's John F. Kennedy Airport had been cleared after a reported shooting, with no shooter found and no injuries reported.
"Preliminary investigation does not indicate shots were fired at JFK," the Port Authority of New York and New Jersey said in a statement released on Twitter at around 11:20 p.m. ET Sunday. "There are no injuries. At this time, no gun shells or other evidence of shots fired has been found."
It said the investigation was continuing.
Chief Harry Wedin, the New York Police Department's chief of special operations, said via Twitter at around 12:20 a.m. ET Monday that all terminals had been searched and cleared, with no shots fired. He said operations at the terminals would resume shortly.
Terminal 8 had reopened by 12:34 a.m. ET, NBC News reported.
A senior law enforcement official said that the incident began when a woman coming off a plane thought she heard gunfire, while two other law enforcement officials said at least one "ear witness" reported hearing gunfire, NBC News reported.
One of those two officials said cheering, clapping and banging from people watching the Olympics may have led to an ear witness' concerns of a fight and shots fired, the report said.
A review of videos at both terminals 1 and 8 showed no evidence of any shooter, NBC News cited officials as saying.
A Port Authority spokesman said planes were not taking off as precautionary searching continued, but planes were landing, NBC News said.
The Federal Aviation Administration said JFK Airport had been placed on a "ground stop" for security, with all inbound flights being held at their origin until Sunday, 11:30 p.m. ET.
In an earlier statement, the Port Authority said police had received reports of shots fired near the departures area at terminal 8 at 9:30 p.m. ET and that the terminal was evacuated as a precaution.
The Port Authority added that about 10:15 p.m. ET, Terminal 1 was also closed after additional calls of shots fired and the Van Wyck Expressway was closed off in the vicinity, it said.
The Fire Department of New York, the Port Authority, the New York Police Department and the Federal Bureau of Investigation had all responded, as a precaution, NBC News reported.